Chapter 7: Membrane Structure and Function Flashcards
allowing some substances to cross it more easily than others
selective permeability
molecules containing hydrophobic and hydrophilic regions
amphipathic molecules
the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids is called what
fluid mosaic modle
the membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids what
weak hydrophobic interactions
form the main fabric of the membrane
phospholipids
determine most of the membrane’s functions
proteins
are bound to the surface of the membrane
peripheral proteins
penetrate the hydrophobic core
integral proteins
integral proteins that span the membrane
transmembrane proteins
cell-surface membrane functions
- Transport
- Enzymatic activity
- Signal transduction
- Cell-cell recognition
- Intercellular joining
- Attachment to the
cytoskeleton and
extracellular matrix
(ECM)
membrane carbohydrates covalently bonded to lipids
glycolipids or glycoproteins
are selectively permeable,
regulating the cell’s molecular traffic
Plasma membranes
can dissolve in the lipid bilayer and
pass through the membrane rapidly
Hydrophobic (nonpolar) molecules
molecules including ions and polar
molecules do not cross the membrane easily
Hydrophilic molecules
allow passage of hydrophilic
substances across the membrane
transport proteins
have a hydrophilic channel that certain molecules or
ions can use as a tunnel
channel proteins
greatly facilitate
the passage of water molecules
aquaporins
bind
to molecules and change shape to shuttle them
across the membrane
carrier proteins
is the tendency for molecules to spread
out evenly into the available space
diffusion
the region along which the density of a
chemical substance increases or decreases
concentration
gradient
The diffusion of a substance across a biological
membrane is what
passive transport
is the diffusion of water across a
selectively permeable membrane
osmosis
is the ability of a surrounding solution to
cause a cell to gain or lose water
tonicity
Solute concentration is the same
as that inside the cell; no net water movement
across the plasma membrane
isotonic
Solute concentration is greater
than that inside the cell; cell loses water
Hypertonic solution
Solute concentration is less than that inside the cell; cell gains water
Hypotonic solution